Vane pumps and motors



May 23, 1967 H. F. VON THLJENGEN ET AL VANE PUMPS AND MOTORSSheets-Sheet 1 Filed Aug. 10, 1965 ATTORWE Y y 3, 1967' H. P, VONTHUENGEN ET AL 3,320,899

AND MOTORS VANE PUMPS 2 Sheets-Sheet 43 Filed Aug. 10, 1965 UnitedStates Patent 3,329,899 VANE PUMPS AND MOTQRS Hubert Freiherr vonThuengen, Friedrichshafen, and Otto Doleschalek, Tettnang, Germany,assignors to Zalrrn radfabrih Friedrichshafen Aktiengesellschaft,Friedrichshafen am Bodensee, Germany Filed Aug. 10, 1965, Ser. No.478,552 Claims priority, application Germany, Aug. 17, 1964,

z 11,034 2 Claims. (Cl. 1tl3ll36) The invention relates to vane typehydraulic pumps and, more particularly, to pumps having radiallyslidable or radially and pivotally movable vanes.

One of the difficulties in connection with vane type pumps is thepressures which develop at opposite sides of the rotor in which oneclearance space of the pump chamber may have a pressure in excess ofmaximum permissible pressure while in the opposite clearance space aconsiderably reduced pressure is effected. Such clearance spaces aregenerally diametrically opposite to each other and in a plane normal tothe suction pressure ports of the pump. As a result of this differentialpressure developing on opposite sides of the rotor, there is anunbalance of force on the rotor which results in pressure oscillationand shock pressures causing premature wear on the casing and the pumpparts. This is, of course, a very undesirable effect.

The present invention has for its object the elimination of suchpressure unbalance and the consequent pressure shock forces andoscillations. Another object of the invention is to provide for theelimination of the above drawback in a very simple, economical, andrugged construction.

Briefly, the invention comprises the provision of small bypass ports inthe clearance spaces of the casing at opposite sides thereof to permitflow therebetween for pressure balancing. Thus, the ports are connectedwith a bypass tube. Accordingly, high pressures are equalizeddiametrically across the pump chamber. However, in order to prevent lossof efficiency due to fluid passage from the suction to the pressuresides of the pump, the pump vanes are made of a thickness larger thanthe diameter of the aforementioned small ports so as to close theseports in sweeping past them.

The arrangement is such that the regions of maximum and minimumpressures in the clearance spaces are diametrically opposed to eachother on a diameter perpendicular to the common diametrical axis of theinlet and outlet ducts. The pressures are equalized without sacrificingloss of outlet pressure or pumping efficiency.

The bypass tube is of relatively large diameter compared to the bypassports so that the flow rate in the tube is small, in fact, very slight.Accordingly, since the pres sures in the clearance spaces alternate fromhigh to low relative to each other, flow in the bypass tube isreversible, but of such low velocity that the bypass arrangement canrespond rapidly to the repetitive pressure variations in the clearancespaces.

A detailed description of the invention now follows in conjunction withthe drawing in which:

FIG. 1 is an elevation in cross-section through a hydraulic pump havingthree radially slidable vanes;

FIG. 2 illustrates a position of the vanes occurring shortly after thevane position of P16. 1;

FIG. 3 illustrates a four-vane pump in elevational crosssection, thevanes being of the radially sliding type; and

FIG. 4 illustrates in elevational cross-section a five-vane pump whereinthe vanes are radially slidable and pivotal.

FIG. 1 illustrates a pump housing having an inlet duct 11 and an outletduct 12 with a rotor 13 rotative clockwise in the pump chamber. The axis14 of the rofor is eccentrically disposed relative to the housing axis15 by eccentricity e.

The rotor 13 carries radially slidable vanes 16a, 16b, 16c, spaced apartand rotating in a clockwise direction. The construction thus far isconventional, the vane edges having a sealing sliding movement againstthe annular wall of the chamber. The invention comprises the addition ofa bypass tube 19 leading from a port 18a in the upper chamber clearancespace 1 to a port 18b in the lower chamber clearance space 2. It will benoted that the vanes have a thickness D greater than the port openingsB.

Attention is called to the phantom line positions of the vanes 16a and1611 which mark off a cell of the pump. It will be noted that theclearance space I initially decreases in volume as these vanes moveclockwise to the full line position. However, with continued movement,the clearance space 1 increases in volume. This decrease and increase involume corresponds to an increase and decrease in pressure within thatspace. In a similar manner, as the cell effected by the vanes 16b and Merotates, the reversed condition is realized in clearance space 2. Inother words, the volume of that space first increases and thendecreases. Accordingly, there is initially a decrease in pressure inclearance space 2 followed by an increase in pressure. It is theseopposing increases and decreases in pressure between the two clearancespaces which cause the shock effects on the rotor and housing. However,by providing the bypass tube 19, the differential pressures areequalized or balanced in order to avoid the pressure differentialstresses.

As seen in FIG. 1, the following events occur:

(a) The casing portion 17a of the upper clearance space 1 forms a cellbetween vanes 16a and 16b.

(b) As vane 16a moves from the phantom to full line positions, thevolume of clearance space 1 decreases.

(c) Flow occurs through port 18a, tube 19, port 18b to outlet duct 12(vane 16c is in phantom line position).

(d) Vane 16c closes port 181) to cut off flow to duct 12.

(e) Vane (full line position) opens port 18!: to afford communication toinlet duct 11.

(f) Clearance space 1 now begins to increase in volume.

(g) Continued movement of vane 16b beyond the full line position causesflow from duct 11 through port 18a, tube 19, port 1% into clearancespace 2 of casing portion 17b, in the cell between vanes 16b and 16c.

(h) Vane 16a closes port 18a to cut off clearance space 1 fromcommunication with tube H (in FIG. 2, this vane in solid lines has justpassed port 18a).

(i) Vane 16b at the same time cuts off flow from duct 11 to clearancespace 2 (in FIG. 2) this vane in solid lines has just passed the loweredge of duct 11, the closing instant being illustrated by the phantomline position.

(j) The volume of the cell between vanes 16b and 160 (clearance space 2)is now decreasing, the pressure rising above that in the cell betweenvanes 16c and 16a (clear ance space 1).

(k) Flow moves from port 185, through tube 19 to port 18a, to effectbalance, and the cycle of communication and cut-ofi between theclearance spaces and ducts is repeated.

Referring to FIG. 3, a four-vane pump with eccentric rotor isillustrated, the vanes being radially slidable wherein rotor 33 ismounted ecc-entrically with eccentricity e in pump housing 39 which hasan axis 35 and upper and lower portions 37a and 37b. The rotor carriesthe four radially slidable vanes spaced 90 apart, 36a, 36b, 36c, and36d. In the full line position, vane 36a has just closed outlet port 32,and in continuing its movement, it reduces the volume of clearance space21, measured off at this time between vanes 36a and 36b. In thesubsequent vane positions shown in dash-dot lines, vane 36c cuts offlower clearance space 22, measured off between vanes 36c and 36d frominlet opening 31. As the rotor continues beyond the phantom lineposition, the volume of clearance space 2.2 will increase initially.When, however, the rotor has moved to a position such that therespective vanes are about 90 from their full line position shown, theclearance space 21 communicates through tube 39 with clearance space 22Which is still measured off between vanes 36c and 36d. This bypassingcommunication occurs for almost 90 of movement of the rotor and effectsa pressure balance across the rotor from top to bottom by virtue ofdelivery of fluid through tube 39 as was the case .in FIG. 1 fordelivery through tube 19. The cycle of communication and cut-off of theports, clearance spaces and ducts follows the principles set forth inthe description of FIGS. 1 and 2, as will be understood by personsskilled in the art.

FIG. 4 shows a five-vane rotor in which the rotor 43 is carried on ashaft 44. The housing has the usual ducts for inlet and outlet, 41 and42, respectively. The vanes 46a, 46b, 46c, 46d and 46@ are radiallyfixed and rotatably disposed on a bearing shaft 45 which is provided inthe center of the pump chamber. Said vanes are slida bly extendingthrough slide pivot inserts 43a, 43b, 43c, 43d and 43:: which arerotatably arranged in said rotor 43 in an gularly fixed relation to eachother. In this instance, the rotor shaft 44 has eccentricity c withrelation to the casing axis 45. The construction thus far described isconventional and the invention is applied thereto by means of port 48ain the clearance space 51 at upper casing portion 47a and of the port48b at the lower casing portion 47b in the clearance space 52, with tube49 connecting the ports.

As in the previous modifications, the vane thickness D is larger thanthe port openings B, and such ports are located in a plane midwaybetween the inlet and outlet ducts 41 and 42.

In operation, as the vanes 46d and 462 rotate from the phantom lineposition to the full line position, the volume of clearance space 52 isfirst increased and subsequently reduced. Accordingly, suction effectsmovement of fluid from the inlet duct 41 through port 48a, tube 49 toport 48b. After vane 46b moves past port 48a, communication for pressurefluid takes place through port 48b, line 49, and port 48a into outletduct 42. This continues until vane 46a cuts off communication betweenduct 42 and port 48a. At that time, the same process is reversed forclearance space 51 which is then a cell between vanes 46c and 461i, allin accordance with the principles hereinabove described.

For all forms of the invention, the bypass tube is made of sufficientlylarge diameter so that balancing flow between the ports occurs at a verylow discharge rate and therefore equalization of forces on the rotor andcasing can occur very rapidly, such balancing flow being relativelyslight in comparison with the pump capacity, as has been hereinabovementioned. The bypass ports are quite short in length so that no seriousresistance to flow with rapid reversal is experienced. The invention isreadily adaptable to any conventional vane pump construction, due carebeing taken to make the bypass port diameters less than the vanethickness.

\Ve claim:

1. In a rotary vane type pump comprising a casing having an inlet and anoutlet duct, a rotor in said casing comprising angularly spaced vanesefiFecting cells for pumping fiuid from said inlet duct to said outletduct, wherein the disposition of said rotor and said vanes in saidcasing effects clearance spaces in said casing at generally oppositesides of said casing, said clearance spaces being intermediate saidinlet and outlet ducts and being subjected to oppositely varyingpressures as said rotor rotates, the improvement which comprises a flowbypass means between said clearance spaces for effecting communicationsof fluid therebetween to equalize pressures in said clearance spaces,

said bypass means comprising ports in said casing opening intorespective clearance spaces, and a bypass tube means connecting theports,

said vanes having a thickness larger than the dimension of said ports soas to cut olf flow therethrough in sweeping therepast whereby pressureis maintained at said outlet duct without bypass fiow loss,

wherein said bypass tube means cornprIses a tube exteriorally of saidcasing and of a diameter sufficiently large relative said ports toeffect relatively low velocity of fluid intermediate said clearancespaces.

2. In a rotary pump as set forth in claim 1, including means formounting said vanes whereby said vanes are individually slidable andpivotal in said rotor.

References Cited by the Examiner UNITED STATES PATENTS 985,091 2/1911VVittig 230-452 2,711,698 6/1955 Bozek et a1. l03136 3,252,284 5/1966Von Thuengen 103-l44 DONLEY I. STOCKING, Primary Examiner.

MARK NEWMAN, Examiner.

R. M. VARGO, W. I. GOODLIN, Assistant Examiners.

1. IN A ROTARY VANE TYPE PUMP COMPRISING A CASING HAVING AN INLET AND ANOUTLET DUCT, A ROTOR IN SAID CASING COMPRISING ANGULARLY SPACED VANESEFFECTING CELLS FOR PUMPING FLUID FROM SAID INLET DUCT TO SAID OUTLETDUCT, WHEREIN THE DISPOSITION OF SAID ROTOR AND SAID VANES IN SAIDCASING EFFECTS CLEARANCE SPACES IN SAID CASING AT GENERALLY OPPOSITESIDES OF SAID CASING, SAID CLEARANCE SPACES BEING INTERMEDIATE SAIDINLET AND OUTLET DUCTS AND BEING SUBJECTED TO OPPOSITELY VARYINGPRESSURES AS SAID ROTOR ROTATES, THE IMPROVEMENT WHICH COMPRISES A FLOWBYPASS MEANS BETWEEN SAID CLEARANCE SPACES FOR EFFECTING COMMUNICATIONSOF FLUID THEREBETWEEN TO EQUALIZE PRESSURES IN SAID CLEARANCE SPACES,SAID BYPASS MEANS COMPRISING PORTS IN SAID CASING OPENING INTORESPECTIVE CLEARANCE SPACES, AND A BYPASS TUBE MEANS CONNECTING THEPORTS,